The present invention relates to a liquid crystal alignment agent, a liquid crystal device produced by using the liquid crystal alignment agent thereof, and a method for alignment of liquid crystal molecules by using the liquid crystal alignment agent. In more detail, the present invention relates to a novel liquid crystal alignment agent used in a method of aligning liquid crystal molecules comprising irradiating the surface of a thin polymer film with light and aligning the liquid crystal molecules without any rubbing treatment, a liquid crystal device and a method for alignment of liquid crystal molecules by using the liquid crystal alignment agent. The liquid crystal alignment agent comprising a polymer having a specific unit structure has characteristics such that the resulting liquid crystal alignment films realize high sensitivity, high heat stability and high light resistance compared to the prior art.
Liquid crystal display devices are display devices utilizing electrooptical changes of liquid crystal. Attention has been drawn to their features such that the devices are small in size and light in weight, and power consumption is small. Accordingly, in recent years, they have undergone remarkable developments as display devices for various displays. Among them, an electric field effect type (TN type) is representative, wherein nematic liquid crystal having a positive dielectric anisotropy is used, liquid crystal molecules are aligned in parallel with substrates at the respective interfaces of a pair of mutually opposing electrode substrates, and the two substrates are combined so that the alignment directions of liquid crystal molecules will cross each other.
With such a TN type liquid crystal display device, it is important to align the long axial directions of liquid crystal molecules uniformly in parallel with the substrate surface and to align the liquid crystal molecules with a constant tilt alignment angle (hereinafter referred to as a pre-tilt angle) to the substrate.
As typical methods for aligning liquid crystal molecules in such a manner, two methods have heretofore been known. The first method is a method wherein an inorganic substance such as silicon oxide is vapor-deposited from an oblique direction to the substrate to form an inorganic film on the substrate, so that the liquid crystal molecules will be aligned in the direction of vapor-deposition. This method is not industrially efficient, although constant alignment with a predetermined tilt angle can be obtained.
The second method is a method wherein an organic coating film is formed on the substrate surface, and the film surface is rubbed in a predetermined direction with a cloth, for example of nylon or polyester, so that the liquid crystal molecules are aligned in the rubbing direction. An organic coating film (called liquid crystal alignment film or alignment film) is usually formed by coating the liquid crystal alignment agent over the surface of a substrate. By this method, constant alignment can be obtained relatively easily, and this method is industrially most commonly employed. As the organic film, polyvinyl alcohol, polyoxyethylene, polyamide or polyimide may, for example, be mentioned. However, polyimide is most commonly employed from the viewpoint of the mechanical strength, chemical stability, thermal stability, etc. As typical examples of polyimide used for such liquid crystal alignment films, those disclosed in JP-A 61-47932 may be mentioned.
The treating method for liquid crystal alignment by rubbing polyimide film is an industrially useful method that is simple and excellent in productivity. The demands for high precision and high performance of liquid crystal display devices have increased and new display systems corresponding to such demands have been developed. For example, a STN (Super Twisted Nematic) system wherein the twist angle of a TN type liquid crystal display is increased, an AM (Active Matrix) system wherein switching elements are formed for individual electrodes, and a FLC (ferroelectric) or AFLC (antiferroelectric) system wherein ferroelectric liquid crystal or antiferroelectric liquid crystal is employed, may be mentioned as such examples. However, various problems of the rubbing method have been pointed out. In the STN system, contrast is high and scratches on the alignment film surface formed by rubbing become display defects. In the FLC or AFLC system, it is difficult to satisfy both high speed response and uniform alignment of smectic liquid crystal only by simple rubbing treatment. In the AM system, the mechanical force or static electricity due to rubbing is likely to destroy the switching elements, and dusting by rubbing tends to lead to display defects. Since the AM system in particular drives liquid crystals with semiconductor devices such as TFT (thin film transistor) and basically requires absolute cleanliness in its semiconductor technology, the a process such as rubbing is not strictly speaking the best method in practical industrial production.
For the purpose of solving such problems, a so-called xe2x80x9crubbing-lessxe2x80x9d alignment method, wherein liquid crystals are aligned without rubbing, has been studied and various methods have been proposed. For example, a method wherein photochromic molecules are introduced to the alignment film surface so that molecules on the alignment film surface are aligned by light (JP-A-4-2844), a method wherein molecular chains constituting an alignment film are aligned by means of a LB film (Langmuir-Blodgett film) (S. Kobayashi et al, Jpn. J. Appl. Phys., 27,475 (1988)), and a method wherein an alignment film is press-bonded on a preliminary alignment-treated substrate to transfer the alignment (JP-A-6-43458) have been studied. However, when industrial productivity is taken into account, these methods can not be said to be useful as substitutes for the rubbing method.
Various methods have been proposed wherein periodic irregularities are artificially formed on the alignment film surface and liquid crystal molecules are aligned along such irregularities. The most simple method of this type is a method wherein a replica having periodic irregularities is preliminary prepared and a thermoplastic film is heated and pressed thereon to transfer the irregularities onto the film (JP-A-4-172320, JP-A-4-296820, JP-A-4-311926 etc.). By this method, it is certainly possible to prepare a film having periodic irregularities on its surface efficiently, but it has been impossible to obtain practical reliability as high as a polyimide film used in the rubbing method. A method having high reliability has been proposed in which a light with high energy, such as electron rays (JP-A4-97139), xcex1-rays (JP-A-2-19836), X-rays (JP-A-2-2515) or eximer laser (JP-A-5-53513), is applied to a polyimide film to form periodic, irregularities on the film surface. However, to use a light source of such high energy can not hardly be said to be an efficient treating method for alignment when industrial production, where the alignment treatment is continuously carried out uniformly over the entire surface of a large size substrate, is taken into consideration.
On the other hand, as an efficient method for forming periodic irregularities on the surface of a polyimide film having high reliability, a photolithographic method may be mentioned. The polyimide is used as an insulating film for semiconductors by virtue of its high insulating property and excellent electrical characteristics. In recent years, a so-called photosensitive polyimide has been developed which is a polyimide having a photocurable nature by itself. There has been an attempt to form periodic irregularities by a photolithographic method using this photocurable polyimide. By this method, irregularities have certainly been formed on the surface of the polyimide film, but since the photocurable polyimide was initially developed as an insulating film, the properties to align liquid crystals have been inadequate. Further, it has been necessary to apply a buffer coating layer (JP-A-4-245224). Consequently, the process has been complex and can not be regarded as an efficient treating method for alignment which can be a substitute for the rubbing method when industrial productivity is taken into consideration.
As a new treating method for alignment which has recently been found, a method has been proposed in which polarized ultraviolet rays, etc. are applied to a polymer film surface to align liquid crystal molecules without carrying out a rubbing treatment. The following reports are available as such examples.
W. M. Gibbons et al., Nature, 351, 49 (1991), Y. Kawanishi et al., Mol. Cryst. Loq. Cryst., 218, 153 (1992), M. Shadt et al., Jpn. J. Appl. Phys. 31, 2155 (1992), and Y. Iimura et al., Jpn. J. Appl. Phys. 32, L93 (1993).
These methods are characterized in that liquid crystals are aligned in a predetermined direction by irradiation of polarized light without requiring a conventional rubbing treatment. These methods have merits such that they are free from problems such as static electricity and scratches on the film surface by the rubbing method, and the process is simple when industrial production is taken into consideration.
The liquid crystal alignment method using irradiation of polarized light proposed here is considered to be an attractive new treatment method for liquid crystal alignment without requiring rubbing treatment, although it is still in a fundamental research stage.
The use of polymer compounds with light reacting radicals at the side chain of the polymer molecules as the raw materials in aligning liquid crystal film has been proposed in the reports up to this point because of the necessity in getting photochemical sensitivity against polarized light. Polyvinyl cinnamate may be a typical example of such material. Cinnamate as such manifests anisotropy by dimerizing at the side chain, initiated by light irradiation, leading to aligning liquid crystals in this case. In another embodiment reported, aligning liquid crystal molecules in a certain direction can be achieved by irradiating polarized light over the film surface in which low molecular weight dichroism azo dyestuff are dispersed into polymer materials. Further, the possibility of the alignment of liquid crystal molecules by irradiation with polarized ultraviolet rays and the like over the specific polyimide film has been reported. In this instance, the alignment of liquid crystals may be manifested by the decomposition of the main chain of polyimides in a defined direction.
Polymer material systems with light reacting radicals introduced to the side chain of a polymer, exemplified by polyvinyl cinnamate, do not show sufficient heat resistance against the alignment, and thus, is not fully reliable in a practical aspect of production yet. In regard to the dispersion of low molecular weight dichroism dyestuff, stability against heat and light is a problem awaiting solution for the dispersion system in view of the practical aspects, as dyestuff that align liquid crystals are themselves of low molecular weight. In addition, although polyimides themselves show high reliability for heat resistance in the method of irradiating polarized ultraviolet rays on specific polyimides, the real possibility of not getting full dependability for future practical use still exists as its alignment mechanism is thought to be resulting from the decomposition with light. Moreover, decreased productivity can be expected due to the high energy for light irradiation required for the satisfactory alignment of liquid crystals.
In these respects, materials proposed up to now for liquid crystal alignment with the irradiation of light are not satisfactory in regard to their alignment strength and stability, in addition to their sensitivity. Therefore, practical use of rubbing-less alignment with light irradiation is an important issue to be considered at present.
An object of the present invention relates to a liquid crystal alignment agent, that can align liquid crystals without a rubbing treatment of the liquid crystal alignment film, by light irradiation over the liquid crystal alignment film. Another object of the present invention relates to a liquid crystal alignment agent of a polymer material system with a specific unit structure, with which uniform and stable alignment of liquid crystals can be effectively achieved, with their high heat stability and high light resistance in regard to the alignment attained.
Inventors finally accomplished the present invention as a result of their eager effort to solve the problems described above. That is to say that the present invention relates to a liquid crystal alignment agent that forms a liquid crystal alignment film comprising of a thin alignment film over a substrate, where irradiation of light or electron rays align liquid crystal molecules without any rubbing treatment, and said liquid crystal alignment agent comprises of a polymer compound having a structure shown in the general formula (1)-(7) below 
wherein R1, R2 and R3 are independently of each other hydrogen, alkyl, substituted alkyl, aryl or propagyl in the main chain of polymer compound with number average molecular weight of 1,000-300,000, and said structure makes a direct bond with either a divalent or trivalent aromatic group at both ends of said structure or with a divalent or trivalent aromatic group making a direct bond at one end while at the other end forming a direct bond with a divalent or trivalent alicyclic hydrocarbon group. The present invention also relates to liquid crystal elements by the use of said liquid crystal alignment agent and also methods of aligning liquid crystals by the use of said liquid crystal alignment agent.
As stated above, not only the initial alignment of liquid crystals alone but also more effective and stable alignment are necessary in order for the practical application of aligning liquid crystals by the irradiation of polarized light from the standpoint of reliability and productivity. In preparing practical industrial application, the selection of a polymer structure having high heat and light stability as well as finding the liquid crystal alignment agent from a polymer material system with broader selection latitude are desirable.
The liquid crystal alignment agent in the present invention relates to the thin polymer film coated and formed on an electrode substrate such as glass or plastic film, so as to align the liquid crystals and to control the pre-tilt angle. Namely, the liquid crystal alignment agent in the present invention is applied and cured to a transparent substrate, such as a transparent glass or plastic film, as combined with a transparent electrode so as to form the thin polymer film, and then irradiating light or electron rays over the film in order to produce a liquid crystal alignment film without the necessity of rubbing treatment. The liquid crystal alignment agent in the present invention is under normal circumstances used in the form of a solution.
The thin polymer film formed with the liquid crystal alignment agent of the present invention, in which having structural characteristics of at least one structure shown in the general formula (1)-(7) in the main chain of the polymer compound forming said thin polymer film, and a divalent or trivalent aromatic group forming the direct bond at both ends of said structure, or either a divalent or trivalent aromatic group making the direct bond at one end while at the other end forming the direct bond with a divalent or trivalent alicyclic hydrocarbon group, so as to achieve effective and uniform as well as stable liquid crystal alignment with the irradiation with light or electron rays, is important in order to achieve the object of the present invention. It is also preferred to have 20 to 100 mole % of the unit structure of the polymer in the structure for the effective liquid crystal alignment. The aromatic or alicyclic group described above can have a substituting group. It is also preferred that the glass transition point of the polymer should be 200xc2x0 C. or higher in order to obtain heat stability of alignment. At the same time, the thin polymer film formed on the substrate can chemically change with the irradiation of light and the resulting reaction product can have the glass transition point of 200xc2x0 C. or higher. Radicals that induce a dimerization reaction or isomerization reaction, such as the radicals shown in the general formula of (8)-(17) 
wherein R4, R5, R6, R7, R8 and R9 are independently of each other hydrogen, halogen, alkyl, substituted alkyl, substituted alkoxy, carboxyl, alkoxycarbonyl or cyano group; are not necessary.
Preferred examples of an alkyl group of substituting radicals shown in the general formula of (1)-(7) described above can be a lower alcohol such as methyl, ethyl, propyl, i-propyl, butyl, i-butyl, s-propyl and t-butyl, in addition to generally used long chain alkyl having up to 24 carbon atoms. Also, preferred examples of substituted alkyl are such as trifluoromethyl, 2,2,2-trifluoroethyl, perfluoroethyl, 3,3,3-trifluoropropyl, perfluoropropyl, hexafluoro-i-propyl, 3,3,4,4,4-pentafluorobutyl and perfluorobutyl of lower alkyl groups containing fluorine, generally used fluorine containing long chain alkyl of up to about 24 carbon atoms, and benzyl and benzyl substituted with halogen, alkyl, alkoxy or alkoxycarbonyl on the benzene ring.
There are no limitations for the polymer compounds of the present invention, as long as the polymer compounds have structural characteristics of at least one structure shown above in the general formula (1)-(7), and divalent or trivalent aromatic groups forming the direct bond at the both ends of said structure, or either a divalent or trivalent aromatic group making the direct bond at one end while at the other end forming the direct bond with a divalent or trivalent alicyclic hydrocarbon, but polyamide, polyurethane, polyurea or polyimide precursor having any one of the structures described above in the general formula of (1)-(7), or polyimide obtained by chemical or heat imidation of a polyimide precursor, are preferred from the view point described above.
Preferred examples of polymer compounds are polyimide with divalent organic radicals shown in the general formula (18) or the formula (19a) and (19b) 
wherein R10, R11, R12 and R13 are of general formulas (20)-(23) 
wherein X1, X2, X3, X4, X5 and X6 are independently of each other a single bond, O, CO2, OCO, CH2O, NHCO or CONH; R14, R15, R16, R17, R18 and R19 are independently of each other hydrogen, halogen, C1-C24alkyl, C1-C24alkyl containing fluorine, aryl, propargyl, phenyl or substituted phenyl; Y1 is O, S, CO, CO2, SO2, CH2, NH, NHCO, Y2xe2x80x94Ar1xe2x80x94Y3, Y4xe2x80x94(CH2) n1xe2x80x94Y5 or Y6xe2x80x94Ar2xe2x80x94R20xe2x80x94Ar3xe2x80x94Y7; Y2, Y3, Y4, Y5, Y6 and Y7 are independently of each other O, S, CO, CO2, SO2, CH2, NH or NHCO; n1 is an integer of 1 to 10; R20 is C1-C5 straight or branched lower alkylene, fluoroalkylene or alkylenedioxy; and further Ar1, Ar2 and Ar3 are independently of each other in the general formulas (24), (25) or (26) 
wherein X7, X8, X9, X10 and X11 are independently of each other single bond, O, CO2, OCO, CH2O, NHCO or CONH; R21, R22, R23, R24 and R25 are independently of each other hydrogen, halogen, C1-C24alkyl, C1-C24alkyl containing fluorine, aryl, propargyl, phenyl or substituted phenyl; m1 is an integer of 1-4 and m2 is an integer of 1-3, but with the proviso that when R14, R15, R16, R17, R18, R19, R21, R22, R23, R24 and R25 are hydrogen or halogen, then X1, X2, X3, X4, X5, X6, X7, X8, X9, X10 and X11 are single bond, and Ra1, Ra2, Ra3 and Ra4 are independently of each other hydrogen, alkyl, substituted alkyl, aryl or propargyl.
Further, when practicality and generality are considered, R10 and R11 in the general formula (18) described above, or R12 and R13 in the general formula (19a) and (19b), are independently of each other selected from in the general formula (27)-(41) described below 
wherein, the C1-C24alkyl group of R14, R15, R16, R17, R18, R19, R21, R22, R23, R24 and R25 in the general formula of (20)-(26) described above can be a lower alkyl group such as methyl, ethyl, propyl, i-propyl, butyl, i-butyl, s-butyl or t-butyl, and additionally generally used long chain alkyl, and an alkyl group containing alicyclic hydrocarbon group such as cyclohexyl and bicyclohexyl. Fluorine containing C1-C24 alkyl groups include fluorine containing lower alkyls such as trifluoromethyl, 2,2,2-trifluoroethyl, perfluoroethyl, 3,3,3-trifluoropropyl, perfluoropropyl, hexafluoro-i-propyl, 3,3,4,4,4-pentafluorobutyl and perfluorobutyl, and additionally generally used long chain alkyl containing fluorine.
The substituting groups in the substituted phenyl radical are for example halogen, alkyl, alkyl containing fluorine, alkoxy, alkoxy containing fluorine, alkoxycarbonyl or alkoxycarbonyl containing fluorine.
The radicals of Ra1, Ra2, Ra3 and Ra4 in the general formulas (18), (19a) and (19b) described above are the same as the radicals of R1 in the general formula (1). Polyamide described above with radicals Ra1, Ra2, Ra3 and Ra4 other than hydrogen can be obtained by the methods described below.
They can be obtained by introducing desired radicals with a preferred ratio by the use of known polymer reactions at the N of an amide radical of polyamide in which Ra1, Ra2, R3a and Ra4 are hydrogen (see T. H. Mourey et al., J. Appl. Polym. Sci., 45, 1983 (1992), and M. Takayanagi et al., J. Polym. Sci., Polym. Chem. Ed., 19, 1133 (1981)).
It is also possible to prepare that the desired substituting radical can be introduced at the N of a diamine monomer compound described below and the desired compound can be prepared by the polymerization reaction by using the obtained compound as a monomer.
Examples of monomer compounds for the production of the di-carboxylic acid component corresponding to R10 in the general formula (18) above are aromatic group or aromatic containing di-carboxylic acid and their acid halide and alkylesterification product such as terephthalic acid, isophthalic acid, 2-methyl-isophthalic acid, 4-methyl-isophthalic acid, 5-methyl-isophthalic acid, 5-aryloxyisophthalic acid, 5-aryloxycarbonylisophthalic acid, 5-propergyloxyisophthalic acid, 5-acetyloxyisophthalic acid, 5-benzoylaminoisophthalic acid, tetrafluoroisophthalic acid, methylterephthalic acid, tetraorthoterephthalic acid, tetrafluoroisophthalic acid, methyterephthalic acid, tetrafluoroterephthalic acid, 2,6-naphthalene dicarboxylic acid, 1,6-naphthalene dicarboxylic acid, 2,6-anthracene dicarboxylic acid, 1,6-anthracene dicarboxylic acid, 4,4xe2x80x2-dicarboxy biphenyl, 3,4xe2x80x2-dicarboxy biphenyl, 2,3xe2x80x2-dicarboxy biphenyl, 2,4xe2x80x2-dicarboxy biphenyl, 4,4xe2x80x2-dicarboxy diphenylether, 3,4xe2x80x2-dicarboxy diphenylether, 2,3xe2x80x2-dicarboxy diphenylether, 2,4xe2x80x2-carboxy diphenylether, 3,3xe2x80x2-dicarboxy diphenylether, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-dicarboxy biphenyl, 4,4xe2x80x2-dimethyl-3,3xe2x80x2-dicarboxy biphenyl, 2,2xe2x80x2-dimethyl-4,4xe2x80x2-dicarboxy biphenyl, 3,3xe2x80x2-dimethoxy-4,4xe2x80x2-dicarboxy biphenyl, 4,4xe2x80x2-dimethoxy-3,3xe2x80x2-dicarboxy biphenyl, 2,2xe2x80x2-dimethoxy-4,4xe2x80x2-dicarboxy biphenyl, 4,4xe2x80x2-dicarboxy benzophenone, 3,4xe2x80x2-dicarboxy benzophenone, 3,3xe2x80x2-dicarboxy benzophenone, 4,4xe2x80x2-dicarboxy diphenylmethane, 3,4xe2x80x2-dicarboxy diphenylmethane, 3,3xe2x80x2-dicarboxy diphenylmethane, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-dicarboxy diphenylmethane, 2,2xe2x80x2-dimethyl 4,4xe2x80x2-dicarboxy diphenylmethane, 4,4xe2x80x2-dimethyl-3,3xe2x80x2-dicarboxy diphenylmethane, 3,3xe2x80x2-dimethoxy-4,4xe2x80x2-dicarboxy diphenylmethane, 2,2xe2x80x2-dimethoxy-4,4xe2x80x2-dicarboxy diphenylmethane, 4,4xe2x80x2-dimethoxy-3,3xe2x80x2-dicarboxy diphenylmethane, 4,4xe2x80x2-dicarboxy benzanilide, 3,4xe2x80x2-dicarboxy benzanilide, 4,4xe2x80x2-dicarboxy diphenylsulfon, 3,4xe2x80x2-dicarboxy diphenylsulfon, 3,3xe2x80x2-dicarboxy diphenylsulfone, 2,2-bis (4-carboxyphenyl) propane, 1,4-bis (4-carboxyphenoxy) benzene, 1,3-bis (4-carboxyphenoxy) benzene, 1,3-bis (4-carboxybenzamide) benzene, 1,4-bis (4-carboxybenzamide) benzene, bis (4-carboxyphenoxyphenyl) methane, 4,4xe2x80x2-bis (4-carboxyphenoxy) diphenylsulfone, 2,2-bis [4(4carboxyphenoxyphenyl] propane, 2,2-bis (4-carboxyphenyl) hexafluoropropane, 2,2-bis [4-(4-carboxyphenoxy) phenyl] hexafluoropropane, 1,5-bis (4-carboxyphenyl) pentane, 1,4-bis (4-carboxyphenyl) butane, 1,3-bis (4-carboxyphenyl) propane, di (4-carboxyphenyl) pentane-1,5-dioate, di (4-carboxyphenyl) hexane-1,6 dioate, di (4-carboxyphenyl) heptane-1,7-dioate and further alicyclic dicarboxylic acid and their acid halide and alkylesterification compounds such as 1,3-dicarboxy cyclohexane, 1,4-dicarboxy cyclohexane, 1,2-dicarboxy cyclobutane, 1,3-dicarboxy cyclobutane, bis (4-carboxycyclohexyl) methane, bis (4-carboxy-3-methylcyclohexyl) methane, bis (4-carboxycyclohexyl) ether or bis (4-carboxy-3-methylcyclohexyl) ether, or the mixture of more than two of these compounds can be used.
In addition, it is preferred to use di-carboxylic acid and their derivatives such as 1,3-dicarboxycyclohexane, 1,4-dicarboxycyclohexane, isophthalic acid, terephthalic acid, 4-methylisophthalic acid, methyl terephthalic acid, 4,4xe2x80x2-dicarboxy biphenyl, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-dicarboxy biphenyl, 4,4xe2x80x2-dicarboxy diphenylether, 3,4xe2x80x2-dicarboxy diphenylether, 4,4xe2x80x2-dicarboxy diphenylmethane or 3,3xe2x80x2-dimethyl-4,4xe2x80x2-dicarboxy diphenylmethane, from the standpoint of sensitivity to the light reaction, as well as the easy availability of raw materials.
Examples of monomer compounds for the production of the diamine component corresponding to R11 in general formula (18) above are aromatic group or aromatic containing diamine compound such as p-phenylenediamine, m-phenylenediamine, 2-methyl-m-phenylenediamine, 4-methyl-m-phenylenedianine, 5-methyl-m-phenylenediarnine, 2,4,6-trimethyl-m-phenylenediamine, 5-aryloxy-m-phenylenediamine, 5-aryloxyrnethyl-m-phenylenediamine, methyl-pphenylenedianiine, 2,5-dimethyl-p-phenylenediamine, 2,6-naphthalenediarnine, 1,6-naphthalenediamine, 2,6-anthracenediamine, 1,6-anthracenediamine, 2,7-diaminofluorene, 4,4xe2x80x2-diaminobiphenyl, 3,4xe2x80x2-diaminobiphenyl, 2,3xe2x80x2-diaminobiphenyl, 2,4xe2x80x2-diaminobiphenyl, 4,4xe2x80x2-diaminodiphenylether, 3,4xe2x80x2-diaminodiphenylether, 2,3xe2x80x2-diaminodiphenylether, 2,4xe2x80x2-diaminodiphenylether, 3,3xe2x80x2-diaminodiphenylether, 4,4xe2x80x2-diaminodiphenylsulfide, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diaminobiphenyl, 4,4xe2x80x2-dimethyl-3,3xe2x80x2-diaminobiphenyl, 2,2xe2x80x2-dimethyl-4,4xe2x80x2-diaminobiphenyl, 3,3xe2x80x2-dimethoxy4,4xe2x80x2-diaminobiphenyl, 4,4xe2x80x2-dimethoxy-3,3xe2x80x2-diaminobiphenyl, 2,2xe2x80x2-dimethoxy-4,4xe2x80x2-diaminobiphenyl, 4,4xe2x80x2-diaminobenzophenone, 3,4xe2x80x2-diaminobenzophenone, 3,3xe2x80x2-diaminobenzophenone,. 4,4xe2x80x2-diaminodiphenylmethane, 3,4xe2x80x2-diaminodiphenylmethane, 3,3xe2x80x2-diaminodiphenylmethane, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diaminodiphenylmethane, 4,4xe2x80x2-dimethyl-3,3xe2x80x2-diaminodiphenylmethane, 2,2xe2x80x2-dimethyl-4,4xe2x80x2-diaminodiphenylmethane, 3,3xe2x80x2,5,5xe2x80x2-tetramethyl-4,4xe2x80x2-diaminodiphenylmethane, 3,3xe2x80x2-dimethoxy-4,4xe2x80x2-diaminodiphenylmethane, 4,4xe2x80x2-dimethoxy-3,3xe2x80x2-diaminodiphenylmethane, 2,2xe2x80x2-dimethoxy-4,4xe2x80x2-diaminodiphenylmethane, 4,4xe2x80x2-diaminodiphenylmethane, 4,4xe2x80x2-diaminodiphenylamine, 3,4xe2x80x2-diaminodiphenylamine, 4,4xe2x80x2-diaminobenzanilide, 3,4xe2x80x2-diaminobenzanilide, 4,4xe2x80x2-diaminodiphenylsulfone, 3,4xe2x80x2-diaminodiphenylsulfone, 3,3xe2x80x2-diaminodiphenylsulfone, 2,2xe2x80x2-diaminodiphenylpropane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminobenzamide) benzene, 1,4-bis (4-aminobenzamide) benzene, 4,4xe2x80x2-(4-aminophenoxyphenyl) methane, 4,4xe2x80x2-bis (4-aminophenoxy) diphenylsulfone, 2,2-bis [4-(4-aminophenoxy) phenyl] propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis [4-(4-aminophenoxy) phenyl] hexafluoropropane, 1,5-bis (4-aminophenyl) pentane, 1,4-bis (4-aminophenyl) butane, 1,3-bis (4aminophenyl) propane, di (4-aminophenyl) pentane-1,5-dioate, di (4-aminophenyl) hexane-1,6-dioate or di (4-aminophenyl) heptane-1,7-dioate. At the same time, diamine having a long chain alkyl radical, such as 4,4xe2x80x2-diamino-3-dodecylphenylether or 1-dodecyloxy-2,4-diaminobenzene, can be used in order to elevate the pre-tilt angle. The mixture of more than two kinds can also be used.
The use of diamine compound such as p-phenylenediamine, m-phenylenediamine, methyl-p-phenylenediamnine, 4-methyl-m-phenylenediamine, 2,4,6-trimethyl-m-phenylenediamine, 4,4xe2x80x2-diamninobiphenyl, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diaminobiphenyl, 4,4xe2x80x2-diamninodiphenylether, 4,4xe2x80x2-diaminodiphenylmethane, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diaminodiphenylmethane, 4,4xe2x80x2-diaminodiphenylsulfone, 2,2-bis [4-(4-aminophenoxy) phenyl] propane is preferred from the standpoint of sensitivity to the photo reaction as well as the easy availability of raw materials.
Examples of monomer compounds for the production of the aminocarboxylic acid component corresponding to R12 and R13 in the general formula (19a) and (19b) above are an aromatic group or an aromatic group containing aminocarboxylic acid compound, such as m-aminobenzoic acid, p-aminobenzoic acid, 4-methyl-m-aminobenzoic acid, 3-methyl-p-aminobenzoic acid, 2-amino-6carboxynaphthalene, 1-amino-5-carboxynaphthalene, 1-amino-6-carboxyanthracene, 2-amino-7-carboxyanthracene, 4-(4-aminophenyl) benzoic acid, 3-(4-aminophenyl) benzoic acid, 4-(3-aminophenyl) benzoic acid, 4-(4-aminophenoxy) benzoic acid, 3-(4-aminophenoxy) benzoic acid, 4-(3-aminophenoxy) benzoic acid, 4-amino4xe2x80x2-carboxybenzophenone, 3-amino-4xe2x80x2-carboxybenzophenone, 4-amino-3xe2x80x2-carboxybenzophenone, 4-(4-amino-3-methylphenyl) o-toluic acid, 4-(4-amino-2-methylphenyl) o-toluic acid, 4-aminophenyl-4-carboxyphenylmethane, 3-aminophenyl-4-carboxyphenylmethane, 4-aminophenyl-3-carboxyphenylmethane, 4-amino-4xe2x80x2-carboxydiphenylmethane, 4-aminophenyl-4-carboxyphenylsulfone, 3-aminophenyl-4-carboxyphenylsulfone, 4-aminophenyl-3-carboxyphenylsulfone, 2,2-(4-aminophenyl-4-carboxyphenyl) propane, 2,2-(3-aminophenyl-4-carboxyphenyl) propane, 2,2-(4-aminophenyl-3-carboxyphenyl) propane, 4-aminophenyl-4-carboxybenzanilide, 3-amino-4xe2x80x2-carboxybenzanilide, 4-amino-3xe2x80x2-carboxybenzanilide, 4-[3-(4-aminophenoxy) phenoxy] benzoic acid, 4-[4-(4-aminophenoxy) phenoxy] benzoic acid, 1-(4-aminobenzamide)-3-(4-carboxybenzamide) benzene, 1-(4-aminobenzamide)-4-(4-carboxybenzamide) benzene, 4-[4-(4-aminophenoxy) phenyl] benzoic acid, 4-[4-{4-(4-aminophenoxy) phenyl} phenoxy] benzoic acid, 4-[4-[2-{4-(4-aminophenoxy) phenyl} isopropylidene] phenoxy] benzoic acid, 4-[4-[2-{4-(4-aminophenoxy) phenyl} hexafluoroisopropylidene] phenoxy] benzoic acid, 4-[4-(4-aminophenoxy) butoxy] benzoic acid, 4-[5-(4-aminophenoxy) pentyloxy] benzoic acid, 4-[6-(4-aminophenoxy) hexyloxy] benzoic acid, 4-[5-(4-aminophenoxy)-1,5-dioxopentyl] benzoic acid, 4-[6-(4-aminophenoxy)-1,6-dioxohexyl] benzoic acid or 4-[7-(4-aminophenoxy)-1,7-dioxoheptyl] benzoic acid, and in addition alicyclic aminocarboxylic acid such as 3-aminocyclohexane carboxylic acid, 4-aminocyclohexane carboxylic acid, 1-aminocyclobutane carboxylic acid, 2-aminocyclobutane carboxylic acid, 4-(4-aminocyclohexylmethyl) cyclohexane carboxylic acid, 4-(4-amino-3-methylcyclohexylmethyl)-3-methyl-cyclohexane carboxylic acid, 4-(4-aminocyclohexyloxy) cyclohexane carboxylic acid or 4-(4-amino-3-methylcyclohexyloxy)-3-methyl-cyclohexane carboxylic acid. In addition, the mixture of more than two of these compounds can be used.
The use of amino carboxylic acid compound such as p-amino benzoic acid, m-amino benzoic acid, methyl-p-amino benzoic acid, 4methyl-m-amino benzoic acid, 4-(4-aminophenoxy) benzoic acid, 3,3xe2x80x2-dimethyl-4-(4xe2x80x2-aminophenyl) benzoic acid, 4-(4-aminophenyl) benzoic acid, (4-amilnophenyl-4xe2x80x2-carboxyphenyl) methane, 3,3xe2x80x2-dimethyl-(4-aminophenyl-4xe2x80x2-carboxyphenyl) methane or 4-aminophenyl-4-carboxyphenylsulfone is preferred from the standpoint of sensitivity to the photo reaction as well as the easy availability of raw materials.
The amount of the repeating unit structure consisting of the structure with a divalent or trivalent aromatic group forming the direct bond at the amide group, or either a divalent or trivalent aromatic group making the direct bond at one end while at the other end forming the direct bond with a divalent or trivalent alicyclic hydrocarbon, is preferably 20-100 mole %, and more preferably 50-100 mole %, from the consideration in achieving stable liquid crystal-alignment.
Polyamide as a polymer compound of the present invention, can have the structure with the direct bond with a divalent or trivalent aromatic group at both ends of the amide group, or either a divalent or trivalent aromatic group making the direct bond at one end while at the other end forming the direct bond with a divalent or trivalent alicyclic hydrocarbon. Dicarboxylic acid, diamine and aminocarboxylic acid without aromatic or alicyclichydrocarbon groups can also be used together in combination with the compounds listed above. Positively identified example are oxalic-acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid or 1,10-decanedicarboxylic acid and their acid halide, acid anhydride or alkylesterification compound as the dicarboxylic acid component. The mixture of more than two compounds can also be used. In addition, the component of the diamine compound can be an aliphatic diamine such as 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane or 1,10-diaminodecane, and further diaminosiloxane such as m-xylylenediamine, p-xylylenediamine or 
wherein m is an integer of 1-10. One or the mixture of more than two compounds selected from these diamine compounds can be used.
Aliphatic aminocarboxylic acid components are for example 3-aminopropionic acid, 4-aminobutyric acid, 5-aminopentanoic acid, 6-amnohexanoic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid or 11-aminoundecanoic acid as the aminocarboxylic acid component, and the mixture of more than two compounds selected from these amninocarboxylic acids can be used.
The ways to synthesize these polyamides have no limitations. In general, the final product can be obtained either by a polycondensation reaction in organic solvent upon charging an equimolar ratio of dicarboxylic acid or their derivatives and diamine, by a polycondensation reaction with one kind of aminocarboxylic acid or by a copolymerization reaction with more than, two kinds of aminocarboxylic acis.
These polycondensation reactions proceed well under the existence of a condensation agent., Examples of condensation agents used herewith are triphenyl phosphite, tetrachlorosilane or dimethylchlorosilane among others when dicarboxylic acid or aminocarboxylic acid are used as monomers or trimethylamine, pyridine or N,N-dimethylaniline among others when dicarboxylic acid halide are used as monomer. Reactions should preferably be carried out in organic solvent, and solvents normally used in the embodiments are for example, N,N-dimethyl formamide, N,N-dimethyl acetoamide, N-methyl-2-pyrrolidone, N-methyl caprolactam, tetrahydrofuran, dioxane, toluene, chloroform, dimethylsulfoxide, tetramethy urea, pyridine, dimethysulfone, hexamethylphosphoramide, and butyllactone or cresol.
The preferable temperature range of carrying out the condensation reaction is about xe2x88x92100xc2x0 C. to 200xc2x0 C.
On the other hand, when said dicarboxylic acid anhydride or alkylester compounds are used as a monomer, the polycondensation reaction in general proceeds well by mixing diamine compounds and then melting in vaccuo without the use of said condensation agent and solvent.
It is important that the number-average molecular weight of the polyamide obtained by the method of preparation described above is between 1,000-300,000, more preferably between 3,000-300,000, in order to make full use of the polymer characteristics. Molecular weight can be determined by the known methods such as gel permeation chromatography, osmometry, light dispersion, and viscometric molecular weight determination.
When the polyamide film is to be formed, said polyamide film can be formed by applying polymerization solution directly over the substrate and heated. In addition, they can be used after pouring the formed polyamide solution into an over excess amount of poor solvents, such as water or methanol, and re-dissolved into the solvent after precipitation recovery. The diluting solutions of said polyamide solution and/or solvent in which the polyamide is re-dissolved after precipitation recovery have no limitation as long as they can dissolve polyamide.
Examples of such solvents are 2-pyrrolidone, N-methyl pyrrolidone, N-ethyl pyrrolidone, N-vinyl pyrrolidone, N,N-dimethyl acetoamide, N,N-dimethyl formamide or xcex3-butyllactone. They can be used by itself or a mixture thereof. In addition, even when said solvent alone can not give homogenous solution, the solvent can be added and used within the range in which a homogeneous solution can be obtained. Example of such are ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitolacetate or ethyleneglycol.
The liquid solution is applied on the substrate, thereby forming the polyamide film over the substrate by the evaporation of solvent. Temperature for this purpose is adequate if the solvent can evaporate, and the preferred temperature is normally 80-200xc2x0 C.
The liquid solution of the liquid crystal-aligning agent thus obtained in the present invention is applied on the substrate by a method such as spincoat or offset printing, thereby forming the thin polymer film by heating under the conditions described above. The thickness of the thin polymer film formed has no special limitation, but 10-3,000 nm is preferred for use in the ordinary liquid crystal alignment film.
Next, light or electron rays are irradiated over the surface of said thin polymer film. There is no limitation for the wavelength of light used, but in general the range preferred is between 100 nm and 400 nm. More preferably, appropriate wavelength should be selected as such with a filter and the like depending on the kind of polymer used. In addition, the duration of light irradiation in general ranges from a couple of minutes to a couple of hours, but it is possible to select a suitable time for the polymer to be used.
Further, the way to irradiate has no limitation, but it is preferred to use polarized light in order to obtain the uniform liquid crystal alignment. In this case, the way to irradiate polarized ultraviolet light has no special limitation radiation can be done with polarized phase being rotated or irradiation can also be done more than twice after changing the angles of incidence of the polarized ultraviolet rays. Even non-polarized ultraviolet rays may be irradiated at the certain inclination angle from the normal of the substrate as long as practical polarization can be achieved.
The filmed sides of two substrates thus obtained after irradiation with polarized light are positioned facing each other and thereby aligning the liquid crystal molecules by holding the liquid crystals tightly The alignment of the liquid crystals thus obtained is heat stable.
Good examples of polymer compounds of the present invention include polyimide precursor in the general formula (42a) and (42b) below 
wherein R26 is a tetravalent organic radical, R26 is a trivalent organic radical, and R27 is a divalent or trivalent aromatic group or a divalent organic radical having an amide group bonded with alicyclic hydrocarbon, and a polyimide obtained by chemical or heat imidization of said polymide precursor.
The radical R27 of the compound in the general formula (42a) and (42b) is preferably selected from the radicals below in the general formula (43)-(48) 
wherein X12-X30 are independently of each other single bond, O, CO2, OCO or CH2O; R28-R46 are independently of each other hydrogen, halogen, C1-C24 alkyl, C1-C24 alkyl containing fluorine, aryl, propargyl, phenyl or substituted phenyl; Ra5-Ra15 are independently of each other hydrogen, alkyl, substituted alkyl, aryl or propargyl; Y8 and Y9 are O, S, SO2, CH2, NH, NHCO or CONH; and m1 is an integer of 1-4; with the proviso that when R28-R46 are hydrogen or halogen, X12-X30 are single bond.
The alkyl radical of C1-C24 on R28-R46 in the general formula above are in addition lower alkyl such as methyl, ethyl, propyl, i-propyl, butyl, i-butyl, s-butyl and t-butyl, and alkyl group including alicyclic hydrocarbon such-as normally used long chain alkyl and cyclohexyl or bicyclohexyl radical. Examples of fluorine containing alkyl radicals are in addition fluorine containing lower alkyl such as trifluoromethyl, 2,2,2-trifluoroethyl, perfluoroethyl, 3,3,3-trifluoropropyl, perfluoropropyl, hexafluoro-i-propyl, 3,3,4,4,4-pentafluorobutyl and perfluorobutyl, and normally used long chain fluorine containing alkyl radical. Examples of a substituting radical for substituted phenyl are halogen, alkyl, fluorine containing alkyl, alkoxy, fluorine containing alkoxy, alokoxycarbonyl or fluorine containing alkoxycarbonyl.
The radical of Ra5-Ra15 in the general formula above are the same as the radical of R1 in the general formula (1) above. The polyimide precursor above, and the polyimide having a radical other than hydrogen at radical of Ra5-Ra15, can be produced by introducing a desired substituting radical in advance at the N position of the amide radical of a diamine monomer compound exemplified below, and by carrying out a polymerization reaction using the thus obtained compound above as a monomer.
In addition, preferred examples of the radical R27 is a radical in the general formula (49)-(56) 
wherein R47 in the formula (51) is halogen, C1-C24 alkyl, C1-C24 alkoxy or C1-C24 alkoxycarbonyl.
The C1-C24alkyl radicals of R47 in the general formula (51) above are in addition a lower alkyl such as methyl, ethyl, propyl, i-propyl, butyl, i-butyl, s-butyl and t-butyl, and an alkyl group including alicyclic hydrocarbon such as normally used long chain alkyl, and cyclohexyl or bicyclohexyl. Examples of C1-C24 alkoxyl radicals are in addition methoxy, ethoxy, propoxy, i-propoxy, butoxy, i-butoxy, s-butoxy and t-butoxy, and alkoxy radical including alicyclic hydrocarbon such as long chain alkoxy and cyclohexyl or bicyclohexyl. The C1-C24 alkoxycarbonyl radicals are in addition methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, i-propoxycarbonyl, butoxycarbonyl, i-butoxycarbonyl, s-butoxycarbonyl and t-butoxycarbonyl, and alkoxycarbonyl including alicyclic hydrocarbon such as long chain alkoxycarbonyl and cyclohexyl or bicyclohexyl radical.
Typical examples of a monomer compound in producing the tetracarboxylic acid component corresponding to R26 in the general formula (42a) above are 1,2,3,4-cyclobutane tetracarboxylic acid, 1,2,3,4-cyclopentane tetracarboxylic acid, 2,3,4,5-tetrahydrofuran tetracarboxylic acid, 1,2,4,5-cyclohexane tetracarboxylic acid, 1-(3,4-dicarboxycyclohexyl) succinic acid, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid, pyromellitic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 1,2,5,6-naphthalene tetracarboxylic acid, 1,4,5,8-naphthalene tetracarboxylic acid, 2,3,6,7-anthracene tetracarboxylic acid, 1,2,5,6-anthracec tetracarboxylic acid, 3,3xe2x80x2,4,4xe2x80x2-biphenyl tetracarboxylic acid, 2,3,3xe2x80x2,4xe2x80x2-biphenyl tetracarboxylic acid, bis (3,4-dicarboxyphenyl) ether, 3,3xe2x80x2,4,4xe2x80x2-benzophenone tetracarboxylic acid, bis (3,4-dicarboxyphenyl) sulfone, bis (3,4-dicarboxyphenyl) methane, 2,2-bis (3,4-dicarboxyphenyl) propane, 1,1,1,3,3,3-hexafluoro-2,2-bis (3,4-dicarboxyphenyl) propane, bis (3,4-dicarboxyphenyl) dimethylsilane, bis (3,4-dicarboxyphenyl) diphenylsilane, 2,3,4,5-pyridine tetracarboxylic acid, their dianhydride and their dicarboxylic acid diacidhalide, and aliphatic tetracarboxylic acid such as 1,2,3,4-butane tetracarboxylic acid, their dianhydride and their dicarboxylic acid diacidhalide. One or more than two kinds of these tetracarboxylic acid and their derivatives can be used as the mixture.
Typical examples of monomer compounds in making the tricarboxylic acid component corresponding to R26xe2x80x2in the general formula (42b) above are 1,2,3-cyclobutane tricarboxylic acid, 1,2,3-cyclopentane tricarboxylic acid, 1,2,4-cyclopentane tricarboxylic acid, 2,3,4-tetrahydrofuran tricarboxylic acid, 2,3,5-tetrahydrofuran tricarboxylic acid, 1,2,4-cyclohexane tricarboxylic acid, 1-(3-carboxycyclohexyl) succinic acid, 1-(4-carboxycyclohexyl) succinic acid, trimellitic acid, 2,3,6-naphthalene tricarboxylic acid, 1,2,5-naphthalene tricarboxylic acid, 1,2,6-naphthalene tricarboxylic acid, 1,4,8-naphthalene tricarboxylic acid, 2,3,6-anthracene tricarboxylic acid, 1,2,5-anthracene tricarboxylic acid, 4-(3,4-dicarboxyphenyl) benzoic acid, 3-(3,4-dicarboxyphenyl) benzoic acid, 4-(3,4-dicarboxyphenoxy) benzoic acid, 3-(3,4-dicarboxyphenoxy) benzoic acid, 3,4,4xe2x80x2-benzophenone tricarboxylic acid, 4-carboxyphenyl-3xe2x80x2,4xe2x80x2-dicarboxyphenylsulfone, 4-carboxyphenyl-3xe2x80x2,4xe2x80x2-dicarboxyphenylmethane and their anhydride and dicarboxylic acid acid halide, and aliphatic tricarboxylic acid such as 1,2,4-butane tricarboxylic acid and their anhydride and these dicarboxylic acid acid halide. In addition, one or more than two compounds selected from these tricarboxylic acid and their derivatives can be used in the mixture.
Typical examples of a monomer compound in making the diamine component of R27 in the general formula (42a) and (42b) above are 4,4xe2x80x2-diaminobenzanilide, 3,4xe2x80x2-diaminobenzanilide, 1,3-di [4aminobenzamide] benzene, 1,4-di [4-aminobenzamide] benzene and diamine in the general formula as illustrated below. 
More than two kinds of diamine component can be also mixed for the use.
Additionally, it is preferred to include 4,4xe2x80x2-diaminobenzanilide, 1,3-di [4-aminobenzamide] benzene and diamine components as shown in the general formula below from the viewpoint of stability for liquid crystal alignment. 
The repeating unit structure having a divalent or trivalent aromatic group forming the direct bond at the both ends of the amide radical described above, or either a divalent or trivalent aromatic group making the direct bond at one end while at the other end forming the direct bond with a divalent or trivalent alicyclic hydrocarbon, are preferably included as much as 20 to 100 mole %, more preferably 50 to 100 mole %, of the total polymer component in view of the stabilization of liquid crystal-alignment.
Further, diamine components generally used in polyimide synthesis can be used as long as they are within the range of manifesting the effect of the present invention. Typical examples as such are aromatic diamines such as p-phenylene diamine, m-phenylene diamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4xe2x80x2-diaminobiphenyl, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diaminobiphenyl, 3,3xe2x80x2-dimethoxy-4,4xe2x80x2-diaminobiphenyl, 4,4xe2x80x2-diaminodiphenylmethane, 4,4xe2x80x2-diaminodiphenylether, 2,2-bis (4-aminophenyl) propane, bis (4-amino-3,5-diethylphenyl) methane, 4,4xe2x80x2-diaminodiphenylsulfone, 4,4xe2x80x2-diaminobenzophenone, 2,6-diaminonaphthalene, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenyl) benzene, 9,10-bis (4-aminophenyl) anthracene, 1,3-bis (4-aminophenoxy) benzene, 4,4xe2x80x2-di (4-aminophenkxy) diphenylsulfone, 2,2-bis [4-(4-aminophenoxy) phenyl] propane, 2,2-bis (4-aminophenyl) hexafluoropropane and 2,2-bis [4-(4-aminophenoxy) phenyl] hexafluoropropane, alicyclic-diamines such as bis (4-aminocyclohexyl) methane and bis (4-amino-3-methylcyclohexyl) methane, and aliphatic diamine such as 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane and 1,10-diaminodecane, and in addition, diamino siloxanes such as m-xylelenediamine, p-xylelenediamine or the general formula 
wherein m is an integer of 1-10.
Moreover, diamines having a long chain alkyl group, such as 4,4xe2x80x2-diamino-3-dodecyldiphenylether and 1-dodecyloxy-2,4-diaminobenzene, can be used in order to elevate the pre-tilt angle. One or more than two kinds of these diamine components can be used in the mixture.
The method of preparation of these polyimides has no special limitations. In general, tetracarboxylic acid and their derivatives are reacted with diamine and polymerized to yield a polyimide precursor and then imidization is done by ring closure. Tetracarboxylic acid dianhydride is in general used as the tetracarboxylic acid and their derivatives for this purpose. The ratio of tetracarboxylic acid dianhydride mole number and the total mole number of diamine is preferably 0.8 to 1.2. The more this molar ratio approaches closer to 1, the more the polymerization degree of the polymer becomes, as in a general polycondensation reaction.
When polymerization degree is too small, the strength of the polyimide film is unsatisfactory for the use and liquid crystal alignment becomes unstable. But if polymerization degree becomes too large, workability during the polyimide film formation may be poor. Therefore, it is important that the number-average molecular weight of polyimide according to the present invention is preferably 1,000 to 300,000, more preferably 3,000 to 300,000, in order to manifest the special characteristics of the polymer. The molecular weight can be determined by the known methods such as gel permeation chromatography, osmometry, light dispersion method, and viscometric molecular weight determination.
The methods of reaction/polymerization of tetracarboxylic acid dianhydride and diamine have no specific limitations, and in general, first class diamine and tetracarboxylic acid dianhydride are reacted in an organic polar solvent such as N-methyl-2-pyrrolidone, N,N-dimethylacetoamide or N,N-dimethylformamide to yield a polyimide precursor and then imidization through dehydration ring closure.
The polymerization reaction temperature of tetracarboxylic acid and their derivatives and diamine can be an optional temperature selected from xe2x88x9220-150xc2x0 C., but most preferably xe2x88x925-100xc2x0 C. In addition, this polyimide precursor can be imidized by heat dehydration at 100-400xc2x0 C. or by chemical imidization by the use of an imidization catalyst such as triethylamine/acetic anhydride, as done under the normal condition.
When the polyimide film is to be formed, said polyimide film can be formed by applying polyimide precursor solution directly over the substrate and imidizing by heating. The polymerization solutions described above itself can be used as the polyimide precursor solution for this occasion, or they can be used after pouring the formed polyimide precursor solution into an over excess amount of poor solvents such as water or methanol, and re-dissolved into the solvent after precipitation recovery. The diluting solutions of said polyimide precursor solution and/or solvent in which polyimide is re-dissolved after precipitation recovery have no limitation as long as they can dissolve the polyimide precursor.
Typical examples of such solvent are N-methyl-2-pyrrolidone, N,N-dimethylacetoamide and N,N-dimethylformamide. They can be used alone or they can be used in a mixture. What is more, even when said solvent alone can not give a homogenous solution, the solvent can be added and used within the range in which a homogeneous solution can be obtained. Examples of such are ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitolacetate or ethyleneglycol.
The temperature for heat imidization over the substrate is an optional temperature selected from 100-400xc2x0 C., and most preferably in the range of 150-350xc2x0 C.
On the other hand, when polyimide is dissolved in solvent, a polyimide precursor solution obtained by reacting tetracarboxylic acid dianhydride and diamine can be used as the polyimide solution after imidization.
The polyimide solutions thus obtained can be used as they are or they can be used after precipitating in poor solvents such as methanol or ethanol, isolating and re-dissolving into the suitable solvent for the use.
The solvent in which the obtained polyimide is re-dissolved can be any solvent without any limitation as long as they can dissolve the polyimide obtained. Examples of such can be 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, N,N-dimethylacetoamide, N,N-dimethylformamide and xcex3-butyllactone.
Any other solvent which alone can not solubilize polyimide can be added to the solvent described above within the range of which they do not affect solubility. Any solvent which can not give a homogenous solution can be used within the range in which homogeneous solution can be obtained. Examples of such are ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitolacetate and ethyleneglycol.
The liquid solution can be applied on the substrate, thereby forming the polyimide film over the substrate by the evaporation of solvent. Adequate temperature for this purpose is at which the solvent can evaporate, and the preferred temperature is normally 80-200xc2x0 C.
The liquid solution of the liquid crystal-alignment agent thus obtained in the present invention is applied on the substrate by a method such as spincoat or decalcomania process printing, thereby forming the thin polymer film by heat calcination under the conditions described above. The thickness of the thin polymer film formed has no special limitation, but 10-3,000 nm is preferred for the use in ordinary liquid crystal-alignment film.
Next, light or electron rays are irradiated over the surface of said thin polymer film. There is no limitation for the wavelength of light utilized, but in general the range preferred is between 100 nm and 400 nm. More preferably, appropriate wavelength should be selected by an appropriate device such as a filter depending on the kind of polymer used. In addition, the duration of light irradiation in general ranges from a couple of minutes to a couple of hours, but it is possible to select a suitable wavelength for the polymer to be used.
Further, the way to irradiate has no limitation, but it is preferred to use polarized light in order to obtain the uniform liquid crystal-alignment. In this case, the way to irradiate polarized ultraviolet light has no special limitation. Irradiation can be done with the polarized phase being rotated, and irradiation can also be done more than twice after changing the angles of incidence of the polarized ultraviolet rays. Even non-polarized ultraviolet rays may be irradiated at the certain inclination angle from the normal of the substrate as long as practical polarization can be achieved.
The filmed sides of two substrates thus obtained after irradiation with polarized light are positioned facing each other and thereby aligning the liquid crystal molecules by holding the liquid crystals tightly. The alignment of the liquid crystals thus obtained is heat stable.
A preferred example of a polymer compound according to the present invention is a polyurethane having the repeating unit shown in general formula (57) below 
wherein R48 and R49 are independently of each other selected from groups shown in the general formula (58)-(69) below 
wherein Ra16 and Ra17 are independently of each other hydrogen, alkyl, aryl or propagyl.
The radicals Ra16 and Ra17 in the general formula above are the same as the radicals R1 in the general formula (2) above. The polyurethane with a radical Ra16 and Ra17 that is a radical other than hydrogen can be obtained by introducing the desired radical at the preferred ratio at the N position of the urethane radical in polyurethane having the radical Ra16 and Ra17 which are hydrogen by using the known polymer reaction (T. H. Mourey et al., J. Appl. Polym. Sci., 45, 1983 (1992) and M. Takayanagi et al., J. Polym. Sci., Polym. Chem. Ed., 19, 1133 (1981)).
Typical examples of a monomer compound in forming diisocyanate corresponding to R48 in the general formula (57) above are 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 4-methyl-1,3-phenylene diisocyanate, 5-methyl-1,4-phenylene diisocyanate, 2,2-bis (isocyanatephenyl) propane, 4,4xe2x80x2-diisocyanate biphenyl, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diisocyanate biphenyl, 4,4xe2x80x2-diisocyanate diphenylether, 3,4xe2x80x2-diisocyanate diphenylether, 4,4xe2x80x2-diisocyanate dipheylmethane, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diisocyanate diphenylmethane, 4,4xe2x80x2-diisocyanate diphenylsulfone, 1,3-cyclohexane diisocyanate and 1,4-cyclohexane diisocyanate. In addition, the mixture of more than two of these kinds can be used.
On the other hand, typical examples of a monomer compound in forming diol component corresponding to R49 in the general formula (57) above are resorcinol, hydroquinone, 4-methylresorcinol, 5-methylhydroquinone, bisphenol A, 4,4xe2x80x2-biphenol, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-biphenol, 4,4xe2x80x2-dihydroxy diphenylether, 3,4xe2x80x2-dihydroxy diphenylether, 4,4xe2x80x2-dihydroxy diphenylmethane, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-dihydroxy diphenylmethane, 4,4xe2x80x2-dihydroxy diphenylsulfone, 1,3-cyclohexane diol and 1,4-cyclohexane diol as preferred example.
Polyurethane as the polymer compound of the present invention can have the structure with a divalent or trivalent aromatic group forming the direct bond at the urethane radical, or either a divalent or trivalent aromatic group making the direct bond at one end while at the other end forming the direct bond with a divalent or trivalent alicyclic hydrocarbon. Diisocyanate compound or diol compound without aromatic or alicyclic hydrocarbon can be used together in combination. Positively identified examples as such are tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate and m-xylylene diisocyanate as the diisocyanate compound. The mixture of more than two of these kinds can be also used. What is more, examples of a diol compound are ethyleneglycol, trimethyleneglycol, tetramethyleneglycol, pentamethyleneglycol, hexamethyleneglycol, diethyleneglycol, triethyleneglycol, m-xylyleneglycol and p-xylyleneglycol. One or more than two kinds of these diol components can be mixed for the use.
The ways to synthesize these polyurethanes have no special limitation. They can be obtained in general by charging an equal mole amount of diisocyanate and diol and carrying out a polyaddition reaction in an organic solvent. These polyaddition reactions can proceed well with a catalyst and the catalyst preferably used here may be for example triethyemine, tributylamine, diisobutylamine, dibutylamine, diethylamine, pyridine and 2,6-dimethylpyridine.
The reaction is preferably carried out in an organic solvent and typical examples of the solvent used are N,N-dimethylformamide, N,N-dimethylacetoamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, tetrahydrofuran, dioxane, toluene, chloroform, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylphsphoramide, butyllactone and cresol.
The preferable range of the polyaddition reaction is the reaction temperature of xe2x88x9220-200xc2x0 C.
It is important that the number-average molecular weight of the polyurethane obtained by the method of the preparation described above is preferably 1,000 to 300,000, more preferably 3,000 to 300,000, in order to manifest the special characteristics of the polymer. The molecular weight can be determined by the known methods such as gel permeation chromatography, osmometry, light dispersion method, and viscometric molecular weight determination.
When a polyurethane film is to be formed, said polyurethane film can be formed by applying polyurethane solution directly over the substrate and heated. In addition, they can be used after pouring the formed polyurethane solution into an over excess amount of poor solvents such as water or methanol, and re-dissolve into the solvent after precipitation recovery. The diluting solutions of said polyurethane solution and/or solvent in which polyurethane is re-dissolved after precipitation recovery have no limitation as long as they can dissolve polyurethane.
Typical examples of such solvents are 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, N,N-dimethylacetoamide, N,N-dimethylformamide or xcex3-butyllactone. They can be used by itself or a mixture thereof. In addition, even when said solvent alone can not give a homogenous solution, the solvent can be added and used within the range in which a homogeneous solution can be obtained. Examples of such are ethyl cellosolve, buty cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate and ethylenglycol.
The liquid solution is applied on the substrate, thereby forming the polyurethane film over the substrate by the evaporation of the solvent. Temperature for this purpose is adequate if the solvent can evaporate and the preferred temperature is normally 80-200xc2x0 C.
The liquid solution of the liquid crystal aligning agent thus obtained in the present invention is applied on the substrate by a method such as spincoat or decalcomania process printing, thereby forming the thin polymer film by heating under the conditions described above. The thickness of the thin polymer films formed have no special limitation, but 10-3,000 nm is preferred for the use in the ordinary liquid crystal alignment film.
Light or electron rays are subsequently irradiated over the surface of said thin polymer film. There is no limitation for the wavelength of light utilized, but in general the range preferred is between 100 nm and 400 nm. More preferably, appropriate wavelength should be selected by an appropriate device such as filter depending on the kind of polymer used. In addition, the duration of light irradiation in general ranges from a couple of minutes to a couple of hours, but it is possible to select a suitable length of time for the polymer to be used.
Further, the ways to irradiate have no limitation, but it is preferred to use polarized light in order to obtain the uniform liquid crystal alignment. In this case, the ways to irradiate polarized ultraviolet light have no special limitation. Irradiation can be done with the polarized phase being rotated, and irradiation can also be done more than twice after changing the angles of incidence of the polarized ultraviolet rays. Even non-polarized ultraviolet rays may be irradiated at the certain inclination angle from the normal of the substrate as long as practical polarization can be achieved.
The filmed sides of two substrates thus obtained after irradiation with polarized light are positioned facing each other and thereby aligning the liquid crystal molecules by holding the liquid crystals tightly. The alignment of the liquid crystals thus obtained is heat stable.
Good examples of polymer compounds of the present invention are polyurea having the repeating unit shown in the general formula (70) below 
wherein R50 and R51 are independently of each other selected from a group in the general formula (58)-(69), and Ra18-Ra21 are hydrogen, alkyl, substituted alkyl, aryl or propargyl.
The radical Ra18-Ra21 in the general formula above are the same as the radicals R1 and R2 in the general formula (3) described above. The polyurea with radicals Ra18-Ra21 whose radicals are other than hydrogen can be obtained by introducing desired the radical at the preferred ratio at the N position of the urea radical in the polyurea having radical Ra18-Ra21 which are hydrogen by using the known polymer reaction (T. H. Mourey et al., J. Appl. Polym. Sci., 45, 1983 (1992) and M. Takayanagi et al., J. Polym. Sci., Polym. Chem. Ed., 19, 1133 (1981)).
Typical examples of monomer compounds in forming the diisocyanate component corresponding to R50 in the general formula (70) above are 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 4-methyl-1,3-phenylene diisocyanate, 5-methyl-1,4-phenylene diisocyanate, 2,2-bis (isocyanatephenyl) propane, 4,4xe2x80x2-diisocyanate diphenyl, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diisocyanate diphenyl, 4,4xe2x80x2-diisocyanate diphenylether, 3,4xe2x80x2-diisocyanate diphenylether, 4,4xe2x80x2-diisocyanate diphenylmethane, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diisocyanate diphenylmethane, 4,4xe2x80x2-diisocyanate diphenylsulfone, 1,3-cyclohexane diisocyanate and 1,4-cyclohexane diisocyanate. The mixture of more than two of these kinds can be used.
On the other hand, typical examples of monomer compounds in forming the diamine component corresponding to R51 in the general formula (70) above are m-phenylene diamine, p-phenylene diamine, 4-methyl-m-phenylene diamine, 5-methyl-p-phenylene diamine, 2,2-bis (4-aminophenyl) propane, 4,4xe2x80x2-diaminediphenyl, 4,4xe2x80x2-diamino-3,3xe2x80x2-dimethylphenyl, 4,4xe2x80x2-diamino diphenylether, 3,4xe2x80x2-diamino diphenylether, 4,4xe2x80x2-diamino diphenylmethane, 4,4xe2x80x2-diamino-3,3xe2x80x2-dimethyl diphenylmethane, 4,4xe2x80x2-diamino diphenylsulfone and 1,3-cyclohexane diamine. Moreover, the mixture of more than two of these kinds can be used.
Polyurea as a polymer compound of the present invention can have the structure with a divalent or trivalent aromatic group forming the direct bond at the urea group, or either a divalent or trivalent aromatic group making the direct bond at one end while at the other end forming the direct bond with a divalent or trivalent alicyclic hydrocarbon. Diisocyanate compound and diamine compound can be used together in combination as long as they do not have an aromatic or alicyclichydrocarbon group. Positively identified examples as such are tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate and m-xylylene diisocyante, and the mixture of more than two of these kinds can also be used. Furthermore, aliphatic diamine such as 1,2-diaminoethane, 1,3-diamino propane, 1,4-diamino butane, 1,5-diamino pentane, 1,6-diamino hexane, 1,7-diamino heptane, 1,8-diamino octane, 1,9-diamino nonane and 1,10-diamino decane as the diamine compound in addition to m-xylylenedianine and p-xylylenediamine. One or the mixture of more than two of these diamine components can be used.
The ways to synthesize these polyurea have no limitation. In general, the final products can be obtained by the polyaddition reaction in an organic solvent upon charging an equimolar ratio of diisocyanate and diamine. Solvents normally used in the embodiments are for example N,N-dimethyl formamide, N,N-dimethyl acetoamide, N-methyl-2-pyrrolidone, N-methyl caprolactam, tetrahydrofuran, dioxane, toluene, chloroform, dimethylsulfoxide, tetramethyl urea, pyridine, dimethylsulfone, hexamethylphosphoramide, butyllactone and cresol.
The preferable range of the polyaddition reaction temperature is under the normal circumstances in the range of xe2x88x9220xc2x0 C. and 150xc2x0 C.
It is important that the number-average molecular weight of polyurea obtained by the method of preparation described above is between 1,000-300,000, more preferably between 3,000-300,000, in order to make the full use of the polymer characteristics. Molecular weight can be determined by the known methods such as gel permeation chromatography, osmometry, light dispersion, and viscometric molecular weight determination.
When polyurea film is to be formed, said polymer solution may be directly applied over the substrate and heated to form the polyurethane film. In addition, they can be used after pouring the formed polyurea solution into an over excess amount of poor solvents such as water or methanol, and re-dissolved into the solvent after precipitation recovery. The diluting solutions of said polyurea solution and/or solvent in which the polyurea is re-dissolved after precipitation recovery have no limitation as long as they can dissolve polyurea.
Examples of such solvents are 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl pyrrolidone, N-vinyl pyrrolidone, N,N-dimethyl acetoamide, N,N-dimethyl formamide or xcex3-butyllactone. They can be used by itself or a mixture thereof. In addition, even when said solvent alone can not give a homogenous solution, the solvent can be added and used within the range in which a homogeneous solution can be obtained. Example of such are ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitolacetate or ethyleneglycol.
The liquid solution can be applied on the substrate, thereby forming the polyurea film over the substrate by the evaporation of solvent. The temperature for this purpose is adequate if the solvent can evaporate, and the preferred temperature is normally 80-200xc2x0 C.
The liquid solution of the liquid crystal-alignment agent thus obtained in the present invention is applied on the substrate by a method such as spincoat or decalcomania process printing, thereby forming the thin polymer film by heat calcination under the conditions described above. The thickness of the thin polymer film formed has no special limitation, but 10-3,000 nm is preferred for the use in the ordinary liquid crystal alignment film.
Light or electron rays are subsequently irradiated over the surface of said thin polymer film. There is no limitation for the wavelength of light utilized, but in general the range preferred is between 100 nm and 400 nm. More preferably, the appropriate wavelength should be selected by an appropriate device such as a filter depending on the kind of polymer used. In addition, the duration of light irradiation is in general ranging from a couple of minutes to a couple of hours, but it is possible to select a suitable length of time for the polymer to be used.
Further, the ways to irradiate have no limitation, but it is preferred to use polarized light in order to obtain the uniform liquid crystal-alignment. In this case, the ways to irradiate polarized ultraviolet light have no special limitation. Irradiation can be done with the polarized phase being rotated, and irradiation can also be done more than twice after changing the angles of incidence of the polarized ultraviolet rays. Even non-polarized ultraviolet rays may be irradiated at the certain inclination angle from the normal of the substrate as long as practical polarization can be achieved.
The filmed sides of two substrates thus obtained after irradiation with polarized light are positioned to facing each other and thereby aligning the liquid crystal molecules by holding the liquid crystals tightly. The alignment of the liquid crystals thus obtained is heat stable.